Fuel Injector Recommendations (GENERAL EFI INFO)!!!
Turbo Mini Forums

err - Page 3 - last message - think i've mentioned it a few other times aswell...

On 28/11/2005 01:51:29 TurboDave said:

Evo - like your thinking but i'm already ahead of you! As you know, i've recently found out the MPi injecotrs are a Whopping 480cc/min. We also know how hard it is to get more oomplah out of the MPi's than 90horses.

What i'm planning on doing is having this 'injector controller' configured such that is anyone follows my instructions, it'll work.

We'll be looking at two injectors per inlet tract - a set distance and angle from the manifold face. I'll reccomend some suitable injectors later. Fuel pressure will be a vacuum referenced 3bar. Or, if so needed, (turbo / high rpm / etc) is more important (than 2005 emissions spec's), 4-5bar vacuum referenced. The injector controller will control both injectors - but cleverly only run one (in each inlet tract) at lower rpm's, bringing the second injectors in at a pre-set point; at which point the fuel count is halved. A 'gain' will also be added to fine-tune the increased flow from runing two injectors at half duty, compared to one at full - resulting in a seamless 'stepover' (a problem, especially with higher-flow injectors).

We plan to have the setup such that you enter a code for the 'start' of injection and 'end' of injection. This code will be determined by your camshaft duration. You will simply select from a spread-sheet your inlet opening and closing points and then look up the code reference for this timing.
It'll also have a digital readout (based on the information calculated from the code) for the '% remaining' countdown on the current injector duty cycle, so you know when you're about to exceed the injection window and promote charge-stealling.

Basically, we want to make it as 'plug and play' as possible... ideally, without the need for buying and installing two wide-band lambda sensors...
I'm going to run it on my turbo for 12 months before releasing it - Suffice to say, if it can fuel a turbo at 20psi and 7000rpm, it'll fuel any a-series....

Edited by TurboDave16V on 30th Nov, 2005.

Good work Dave...

I should soon have the cam measurments from an MPi if you still need them :)

Alex

AlexF

what are the main differences when going forn a N/A injection setup to a Turbo setup?
I am just starting the fuel injection thing and will be running 2 680cc injectors to start with on a throttle body. The injectors will be running sequencialy.
Has anyone got a N/A systems running?

people have done...

the guy who runs pole star... but thats only really a wet manifold.

Alex

AlexF

Nigel,

The most simplest math:

A nat-asp works at 1-bar air presure.
If you're working at one bar boost this is 2-bar absolute. Hence, you need 100% (double) whatever injectors you were running in an equivalent nat-asp.

The BSFC is also higher however for a turbo, so you need a slightly larger injector again.

If you plan to run more than 1-bar boost - you'll need (again) a larger injector...

Guys I am running a polestar ecu not the mega crap OMEX??? the polestar is already running in N/A mode at 120bhp+, Neil the guy from polestar and me are now protoyping a Turbo systems, it seems most of the problems seem to be with getting something running hence why I have been the hack mini for polestar, half the cost of the Omex and it works??? I was not impressed by Omex at all?
I will let you know how we progress but at the mo we are dealing with turbo related problems and not general running probs..
hope to have a basic setup by march..?
Today I ran over 1 bar of boost and she flew16psi down the local dual carriage way (carb). so the injector system will be set for a power output of 160bhp
and since we already have a single injector runnnig 120bhp + we should be ok for 160bhp with 2 in sequential mode and maybe an extra high boost one?
Putting injectors in the inlet manifold is not the way to go, the fuel/air do not have time to mix.

Edited by TurboDave16V on 4th Dec, 2005.

Dave,

Think I understand what you are saying, yes there will be fuel left lying around. when I say sequential I am talking about how the injectors are triggered not where they are placed.
I am going to try and have 2 injectors in a throttle body so I guess you could call that a 'wet manifold' or 'electronic carb'
Not sure what the end difference would be, ie drivability..over an injector per port set-up?

I think Dave's point of view is that if you only end up with something that is an electronic SU, what is the point of expending a lot of time effort and money if the end result is no superior to the SU?

I also personally agree, if I am going to spend £1000 (which is a realistic figure I believe to achieve injection), it needs to significantly improve on an SU.

Tom,

Yes it has to be better and in N/A mode the car already is far far smoother and with slightly more power at lower RPM, also the throttle responce is better.
The car is so much more drivable, it may not make any difference to the race guys but I use my turbo as much as possible on the road, so am always on off boost and anything that makes the transition to full boost quicker/smoother is a help.
Also I then have the ablity to play with it myself instead of needing a wizard in SU needle profiles.
It will also meen the traction control will be more affective as I can cut/change the injector timing and not the ignition (or both).
It does have to be said that the Standard SU I currently run with only a machined needle is the very good. I have no other mods to it, thats impressive.

It will be better for sure, especially as the needle profile on our engines is ultimately limted by the profile it needs for maximum boost; leading to a richer mixture at cruise than would be preffered for good economy.

Be wary of 'cutting' the fuelling under boost with the traction control; This needs exceptionally carefull consideration

Hi,
Traction control cutting the fuel won't be a problem on a 4 port head, but you could still get some fuel in the cut cylinder on an A series, which could cause a seriously weak mixture.
As Dave says.. if on boost could be catastophic! You would need to cut the spark as well, now you need to cut the spark on the same cylinder, that means a phase sensor at least......
Cheers,
Gavin. :)

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I am surprised that retard alone isn't enough... I had my engie set on tons of retard over 20% throttle at 2000 through to redline in my map (basically on the over-run). Flames and popping happened, and boy did it pull the revs and slow the car down! Great for racing, bad when driving along deansgate between the traffic lights every 100ft.

Edited by TurboDave16V on 6th Dec, 2005.

yeah I think we will leave cutting the injectors until we know more, will leave it as it is, cutting just the spark for now.
Flames out the back dave OK if you don't like the guy behind?

Now on to the rising rate FPR.
I have found a US company called Automotive Inc and they do a set 1.1 ratio fpr i.e for every psi of boost the fuel pressure rises by 1 psi or an adjustable one 1.1 to 10.1, nice bit of kit, was thinking using of one, trying to get them to send one to my other company in the states..check them out..
automotiveinc.com p/n 13109 1.1

I'm (now) going to avoid using one if possible, having done a little research into them.

Basically, nothing beats a nice reliable vacuum referenced 1:1 fuel pressure regulator.

What is wrong with the standard Pressure regulator on the Turbo ? it seems to work ok upto 16psi and my fuel pres gauge says it is rising at the same rate as boost pressure ?? Don't lets forget that the pump in question is used on about 70% of injection cars at the time of Met Tur manufacture !!!

Jaguar prototyped a system a few years ago with a X type 3.5L Supercharged car what they found was they could deliver less fuel to the injectors by lowering the pressure, then giving full flow at the calibrated pressure for the injectors and upto 10% overflow by "over" pressurising the system, unfortunately I don't know about the reliability issues that may have been incurred

Except that you won't see one of these on the road

Thanks
Kind Regards Martin

http://www.mra-minis.co.uk

Edited by TurboDave16V on 6th Dec, 2005.

Yes I have heard some adjustable fpr's can be unreliable, I think I will settle for the 1:1 ratio.

Good call that man!

So how's the timescale for all this looking Nigel? Is this the 'winter' project? - I assume your mini doesn't see a salty road if you can help it!

The time scale is roughly to have something working by april, I'm also pretty skint as the wife is now a uni student, also polestar have other things doing as well.
Yeah I do if I have to otherwise I just drive it on the dry days, didn't have the inlet manifold connected and the other morning it was -2 so I was pushing my luck and yes it did freeze the carb, bloody thing wouldn't start again right on the busy gatwick roundabout, had to push it around the roundabout, what a laugh!
Who are these people who say leave the manifold disconnected? (mini mags)...
Will keep you posted and post some pics when I get everything machined up.
Was also thinking of a stainless turbo elbow 50.8mm? and just sleeve it to the stainless downpipe?

Just had a read through this.

I assume the problems with the DTA you used, were due to it running batch fire only ? My P8Pro can run proper sequential, and you can adjust end of injection.
Based on that, would the P8Pro be an option ?

When I first got the Haltech E8 ecu's I used recently, I thought the EOI angle they seemed to use was a little weird, with most base maps being set at around 330-450deg BTDC

I thought, surely this will fire against a closed valve ?? and yes.
Apparently Motec also prefer this route.

I would have thought myself, that firing whilst the valve was open was the correct way to do things, and is apparently what Bosch imply in their blue book.

Perhaps in the real world it doesnt matter so much ( at least on 4 port cars ) Both Subaru and Cossie are running fine, Subaru with 400BTDC at 0rpm rising to 500BTDC at max rpm.
I did alter the Cossie admittedly, its at 270 rising to 360 BTDC

If you were to time EOI to fire before the inlet valve opens, would that fix the charge stealing issue ?
It sounds like thats almost what you are trying to do, finish injection, before the "robbing" valve opens ? Except I think you are implying you still intend to open the injector only when the correct inlet valve is open, rather than before it opens ?

9.85 @ 145mph
202mph standing mile
speed didn't kill me, but taxation probably will

I know how the P8 works from a mates mini - but I still don't think it'll do everything needed - BUT - no harm in not giving it a try.
Start of injection, and swinging the injection point about is the first step - AND - having the injectors as close to the valve such that the dynamic injection start point changes little (with reference to crank position) for all rev ranges; that's to say the time between the fuel leaving the injector and reaching the valve is as near as dammit the same for all cases.

BUT - don't mount it so close that fuel 'puddles' on top of the 'inactive' valve...

From there on in, you're on your own...

Is the charge robbing scenario more of a problem at low rpm's or at higher ??

Was having a read through here, which has shed some light on the matter for me
http://www.emeraldm3d.com/em_projects_Aseries.html

I also read throughout the forum....

Rover have an "injector per port" system with 2 injectors.
Obviously this cant be sequential, so how do they get around the problem ?

Surely running a setup like that will make matters worse than a 4 inj sequential system ?

9.85 @ 145mph
202mph standing mile
speed didn't kill me, but taxation probably will

The Rover MPi system used two (total) 460cc injectors - one per inlet port - which were fired sequentially; sequentially in that when the port was 'active' the appropriate injector was firing.

They weren't firing sequentially in that injector A fired, then B, then A, then B, etc... It was AABBAABBAABBAABB.....

having read carefully what's involved in injecting the siamesed 5 porter since some time, I've run away from this and collected parts to use twin carby...
then I now have access to an mpi complete set up which I would like to use in combinaison with an emerald unit:
the mpi mems will deliver fuelling at anything under boost , then the emerald unit will inject a "laser beam" fuell stream directed precisely at each valve tulipe, using some 42lb lucas disc type injectors , the mpi unit should give enough fuell for 80 bhp, waiting some 150/160 one out of mine I would only need requirement for 80 bhp which could fall into the tiny injection window.
what's your though please?
fab